1. Field of the Invention
The present invention relates generally to a system for sensing an object, or parts thereof, which is located in the seat of a motor vehicle. In particular, the invention relates to a machine for calibrating and verifying the calibration of an occupant detection system in a vehicle.
2. Description of the Prior Art
Occupant restraint systems for use in vehicles are well known in the art. One such occupant restraint system includes a crash sensor, an inflatable airbag, and an actuation circuit that controls deployment of the airbag in response to an output from the crash sensor. The crash sensor can be an accelerometer that provides an electrical signal having a value functionally related to the vehicle""s deceleration. The actuation circuit includes a squib operatively connected to a source of inert gas.
During a crash condition of a vehicle, the vehicle""s accelerometer provides a signal indicative of a such crash condition. The actuation circuit thereby applies a current through the squib which causes the squib to ignite. When the squib ignites, the source of inert gas discharges gas into the airbag, which results in the inflation of the airbag.
Certain vehicles have both a driver side airbag and a passenger side airbag (xe2x80x9cdual airbagsxe2x80x9d). If such a vehicle is occupied only by the driver and is involved a crash, deployment of the passenger side airbag is unnecessary. Unnecessary deployment of the passenger side airbag can increase the cost of repairing the vehicle. If the passenger side is occupied by an occupant below a certain weight threshold or an infant, it may be desirable to suppress or otherwise regulate the manner in which the airbag is deployed. Since a large percentage of vehicles in use are occupied by only the driver, it is desirable to be able to detect if a passenger is present in the vehicle and deploy the passenger side airbag during a crash only if the passenger is, in fact, present.
Occupant detection systems are designed to measure the presence of an object, which may include the measurement of weight, on a vehicle seat to determine whether a passenger airbag should be suppressed. A typical occupant detection system includes a sensor and an electronic control unit for processing data from the sensor. The data corresponds to the weight on the vehicle seat. The electronic control unit processes the data and provides an xe2x80x9cenable-deploymentxe2x80x9d output to a sensing and diagnostic module, if the weight on the seat is above the required threshold.
The occupant detection system is designed to suppress or otherwise regulate the deployment of the occupant restraint system. Vehicle manufacturers calibrate and verify the calibration of the occupant detection system. A conventional calibration and verification system drops a weight on the vehicle seat. Data corresponding to the weight is output from the sensor. The data is processed by the electronic control unit and calibration values are calculated. The calibration values are stored in an EEPROM. Once again, a weight is dropped on the seat. Data corresponding to the weight is processed by the electronic control unit and verification values are calculated. The calibration and verification values are compared. If the calibration and verification values are within a specified tolerance, the occupant detection system is acceptable for use.
The weight of a conventional calibration and verification system is attached to a cable. The cable is retracted onto a pulley to move the weight to an initial position from which the weight is dropped. The actual distance that the weight is dropped is limited to the length of the cable and the ability to accurately control the retraction of the cable onto the pulley. If the drop distance is not consistent and accurate, then the force of impact of the weight against the vehicle seat will vary. In addition to the inconsistent and inaccurate drop distance, the weight of the cable contributes to the drop weight. The conventional calibration and verification system also does not measure the drop weight. Consequently, the contribution of the weight of the cable to drop weight is unknown. Hence, the force of impact of the drop weight against the vehicle seat is unknown. Moreover, the conventional calibration and verification system does not properly align the drop weight with the seat. There is no means for determining whether the seat is properly positioned. Lastly, frictional affects on the drop weight are not measures by the conventional calibration and verification system. As a result, the affects of friction on the drop weight are unknown. This affects the velocity and thus, the force of impact of the drop weight against the seat. If the drop weight is not properly and consistently applied by the calibration and verification system, then the occupant detection system cannot be properly calibrated and verified and the airbag can improperly deploy.
What is needed is a calibration and verification system that accurately measures the drop weight, the frictional affects on the weight drop, and the drop distance. Moreover, a system is needed that properly aligns the drop weight with the seat.
The present invention relates to a calibration and verification system for an occupant detection system. The calibration and verification system accurately measures the drop weight, the frictional affects on the weight drop, and the drop distance of the weight.
A weight-drop machine according to one embodiment of the invention comprises a base. A lift frame is supported for movement relative to the base. A keeper plate is supported in a fixed position relative to the base. A displacement element is supported in a fixed position relative to the base and the lift frame. The displacement element is adapted to move the lift frame relative to the base. The lift frame is adapted to support and lift a pallet toward the keeper plate to cause the pallet to engage the keeper plate so that the pallet is prevented from further movement.
Another weight-drop machine according to the present invention comprises a bridge, a frame, and a weight supported for movement relative to the frame. The frame is supported for movement relative to the bridge in a direction having both a horizontal component and a vertical component of movement in a single motion.
Yet another weight-drop machine according to the present invention comprises a base, a sensor bracket supported for movement relative to the base, and one or more sensors supported relative to the sensor bracket. The one or more sensors are adapted to sense the position of a vehicle seat supported by the base frame.
Still another weight-drop machine according to the present invention comprises a drop weight including a guide shaft, a bearing supporting the guide shaft for movement, and a sensor connected between the guide shaft and the bearing for measuring displacement of the guide shaft relative to the bearing.
A towel bar lift may be provided for lifting a towel bar for operating a manual seat lock mechanism. The towel bar lift comprises a base and a lift frame supported for vertical and pivotal movement relative to the base. The lift frame has a cantilevered portion that is adapted to extend over the base and under a towel bar and further move upward away from the base and into engagement with the towel bar to move the towel bar upward.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.